AbbVie Inc., the Abbott Laboratories spinoff, has recalled more than 28,520 bottles of the thyroid-hormone replacement therapy Synthroid over a labeling error. It is the second recall of the drug in six months. Synthroid is a synthetic thyroid hormone used to treat hypothyroidism, when the thyroid gland doesn't produce enough natural thyroid hormone. One lot of 150-microgram Synthroid tablets was recalled because a bottle was found to contain a lower dose, AbbVie spokesman Greg Miley said Friday. The voluntary recall began in early December, when AbbVie was still part of Abbott. The company said it was due to a manufacturing error and has taken corrective action. AbbVie isn't aware of any increase in patient complaints or adverse events associated with the error.